The present invention relates generally to the field of packaging, and more specifically to a plastic material suitable for manufacturing radio frequency sealable (“RF-sealable”) packaging material.
In the packaging industry, traditionally, a “clamshell blister package” refers to a plastic package formed from a pair of layers of thermoformable plastic. An article to be packaged is retained between the layers. Typically, the layers, which may be unitary, are hinged along a common edge and are sealed. Well-known sealing techniques include, for example, heat application, use of chemical adhesives, and radio frequency sealing (“RF-sealing”). An example of a clamshell blister package is disclosed in U.S. Pat. No. 5,788,105, the entirety of which is incorporated herein by reference. Other packages may require sealing besides those having clamshell parts, such as two-piece packages.
In many packaging applications, RF-sealing is the preferred technique to seal the package. The layers for RF-sealable packages are usually composed of polyvinyl chloride (PVC), at least in part because this material is easily RF-sealed. However, the industry in recent times has attempted to move away from the use of PVC packaging material, as it is perceived as less environmentally friendly than other possible materials. For example, the European market has searched for a number of years for an alternative material to PVC, due to Europe's propensity to incinerate waste. One such alternative material is polyethylene terephthalate (PET), a common type of polyester.
However, to seal a blister manufactured from PET plastic, a method other than RF-sealing must generally be used because PET is much less polar than materials that are readily RF-sealed. As such, it has been difficult to provide a thermoformable PET plastic material for packaging due to the inability to effectively RF-seal the material.
Accordingly, there is a need in the art to provide an improved RF-sealable, packaging material that is composed of compounds perceived as more environmentally friendly than PVC.
There is a further need in the art to provide an improved thermoformable packaging material.
There is an additional need in the art to provide a process for manufacturing an RF-sealable material for packaging that provides perceived environmental benefits similar to that of PET, and provides RF-sealing capabilities comparable to PVC.